As a metropolitan area network technique, World Interoperability for Microwave Access (WiMAX) is based on the 802.16 series of wireless standards, and particularly the 802.16d and 802.16e wireless standards and the working frequency bands are 2.3 GHz, 2.5 GHz and 3.5 GHz. One base station can provide a maximum downlink data transmission rate of 40 Mbps for multiple fixed users within a radius of 3 km to 10 km and a maximum downlink data transmission rate of 15 Mbps for multiple mobile users within a radius of 3 km. The greatest advantages of WiMAX are wide coverage working distances and availability in mobile environments such as automobiles and cruises.
Wireless fidelity (WiFi) is a short-range radio transmission technique based on the IEEE 802.11b standard. WiFi supports radio signals accessed from the Internet within hundreds of feet. The greatest advantages of WiFi are high transmission speed, which may be as high as 11 Mbps. Additionally, wiring is not needed for WiFi. Since it is not limited to conditions of wiring, it is quite suitable for mobile office users.
Along with the development of the WiMAX technology, WiMAX users propose a new demand for facilitating household use. That is, WiMAX and WiFi are combined, a Customer Premises Equipment (CPE) wirelessly connected with an external WiMAX is used in the home, to transmit videos and data broadband contents received through WiMAX to devices, such as a set-top box, a mobile phone and a PC, through WiFi, such that the user can view or use them. The frequency band used by 802.11b/g WiFi is 2400 MHz-2483.5 MHz, and the channels used are channels 1-13, with a bandwidth of 22 MHz for each channel; the frequency band used by the 2.5 GHz-WiMAX is 2496 MHz-2690 MHz and the bandwidth of the channel commonly used is 5 MHz or 10 MHz. It can be seen that the interval between the frequency bands used by the 2.5 GHz-WiMAX and WiFi is about 13 MHz; the frequency band used by the 2.3 GHz-WiMAX is 2300 MHz-2400 MHz and the bandwidth of the channel commonly used is 8.75 MHz. It can be seen that the frequency bands used by the 2.3 GHz-WiMAX and WiFi are overlapped at sidebands. In view of the above analysis, when WiMAX and WiFi coexist, interference between WiMAX Radio Frequency (RF) signals and WiFi RF signals is prone to occur, which greatly reduces the data transmission rate.
In the prior art, the band interval between the frequency bands used by WiMAX and WiFi is generally enlarged by reducing the frequency bands used by WiMAX and WiFi, in order to decrease the interference between WiMAX RF signals and WiFi RF signals as much as possible. For example, the frequency band used by WiMAX is limited to 2525 MHz-2690 MHz, or the frequency band used by WiFi is limited to 2400 MHz-2452 MHz. Unfortunately, although the above method can decrease the interference between WiMAX RF signals and WiFi RF signals, it wastes mass frequency spectrum resources.